Draft device for locomotives.



W. J. BOHAN.

DRAFT DEVICE FOR LOCOMOTIVES.

APPLICATION FILED APRJ. 19:1.

1,300,335". Patented Apr. 15,1919.

2 $HEETSSHEET 1- W. J. BOHAN.

DRAFT DEVICE FOR LOCOMOTIVES.

APPLICATION FILED APR. 7. 1917.

Patented Apr. 15, 1919.

2 SHEETSSHEET 2.

M2 m1 W W W1 TNESSES:

/QM'. I ATTO EY WILLIAM J. 0 m sr'jrA'Un, lviiunfisorin DRAFT DEVICE non LOCOMOTrVES. I r

Specification of Letters Patent.

. ApplicationfiledApril7,19 17.v serialiveico ison= To all whom it may concern:

Be itknown that I, WILLIAM J. BoHAN, a citizen of the United States, residing at St. Paul, in the county of Ramsey and State of Minnesota, have invented a certain new and useful Improvement in Draft Devices for Locomotives, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This invention relates to improvements in draft devices for locomotives.

One object of the invention is to provide an attachment or device for locomotives for increasing the efficiency of the locomotive by promoting a more uniform draft than now usually obtained.

Another object of the invention is to provide a draft arrangement adapted for insuring a substantially uniform draft through all the fire tubes of the boiler.

In the drawing forming a part of this specification, Figure 1 shows a longitudinal section of the front end of a locomotive with my improvements in connection therewith. And Fig. 2 is a vertical, transverse section, taken substantially on the line 22 of Fig.

In said drawing, 10 denotes the front flue sheet of the locomotive boiler, the latter having the usual outer shell 11 and series of fire tubes 1212. The smoke-box of the locomotive is formed in the usual manner by a shell extension 13, the joint between the shell 11 and extension 13 including an interposed annular strip 14 between the over-lapped riveted edges, as clearly appears in Fig. 1. From the smokebox extends the funnel 15 in the usual man ner.

My improved draft device is located in the smoke-box and, as shown, comprises what I term a draft cone A in combination with a suction or exhaust fan B. The draft cone A is formed of sheet metal and has its larger end adjacent the tube sheet 10. At said end, the cone is shaped to conform to the outline of the series of fire tubes 12, that is, the upper portion of the cone is somewhat flattened, as indicated at 16 in Fig. 2, whereas the lower portion is substantially truly circular, as indicated at 17. Said larger end of the cone is butted against the flue sheet 10 and an air-tight joint is formed therebetween preferably by cementfilling 18-, as shown in Fig. "12 :Said .coneA' is supported in proper position by any suitable means such as the series of bracing clips 19-19, and it will be understood that the sheet metal cone A is formed of as many pieces or sections as may be necessary to produce the required shape and preferably the longitudinally extending meeting edges of adjacent sections are edgebutted and the sections secured together by an over-lapped strip 20.

At its forward or smaller end, the cone A has a substantially circular mouth, as indicated at 21, and the same fits into the intake orifice or mouth 22 of the exhaust fan B. The intake mouth or orifice of the fan B is of generally flared circular form, that is, a diametrical section at any point thereof will give a true circle, the diameters of the circles varying at different points. The flare of the mouth is obtained by curving the surface in such manner that a longitudinal section through the mouth will produce two opposed arcs of circles, the

radius of said arcs (as indicated by the reference R in Fig. 1 of the drawing) being made the same as the minimum diameter of said mouth (as indicated by the reference D in said figure.) The outlet orifice 23 of the fan which extends into the funnel 15, is formed in a similar manner. This construction of the intake mouth and outlet orifice is employed inasmuch as experience has determined that it 7 produces the maximum efliciency.

The fan proper is mounted on a shaft 24 which I may be. rotated by any suitable means which I do not deem it necessary to illustrate and describe.

Where the cone A unites with the intake scribed, the combination with a flue sheet the minimum diameter of said orifice equal- 10 of a boiler and the fiues associated thereingthe radiusofcu-rvature of said surface. with, of a hollow con li'ke conduit'havifig" Inivi itness tharl' claim the foregoing I its larger end fitted over said flue sheet," have hereunto subscribed my name this 22nd and an exhaust 'fan having an intake orifice day of March, 1917.

in communicationrwith said conduit at theh I WM. J. BOHAN. I sma'ller end of the latter, said intake orifice Witnesses:

of the fan being of circular emsssectien GEO; F; ENDIGOTT,

and having an outwardly curved surface, THos. R. WILLIAMS. 

